The Scott Trust has announced it has decided to press ahead with its sale of the Observer to Tortoise Media. The decision would “protect the Observer’s future, championing the voice of liberal values and investing in exceptional journalism, while building its digital offering”, it said last week.

Tortoise is run by former director of BBC News James Harding, who has promised to continue to publish the Observer on a Sunday and build up the newspaper’s digital presence by combining it with the group’s podcasts, newsletters and live events.

The deal, currently agreed in principle, will also result in £25m of investment in the Observer by Tortoise, whose investors will now include the Scott Trust, it has been revealed. Employees have been told there will be no staff job losses.

However, the move to pass ownership of the world’s oldest Sunday newspaper to Tortoise has been opposed by journalists at the Guardian Media Group, which owns the Observer.

Last week the joint Guardian-Observer chapel of the National Union of Journalists (NUJ) held a two-day strike in a bid to delay the deal and consider alternatives, including keeping the Observer at the Guardian.

After the Scott Trust revealed it was pressing ahead with the deal, the NUJ chapel issued a statement: “We urge the company to pause, reconsider all options and the impact this will have on the standing of the Observer and the long-term future of liberal journalism,” it stated.

Two further days of strikes are planned to take place this week, while the Guardian and Observer NUJ chapel will meet to consider further actions, it added. In the wake of the Scott Trust’s decision to sign off the deal, Harding said: “We’re honoured to have been entrusted with a paper admired for its liberal values and its humane temperament and excited at the prospect of combining the Observer’s talent for reporting the stories that are unseen and neglected, its eye for photography, its love of the arts and food and its wonderfully independent thinking with Tortoise’s ability to take time on investigations, podcasts, data and digital journalism.

“We will invest in more journalists and increase the editorial budget. We hope that together we can honour its history, delight today’s readers and win the admiration of a generation of readers to come.”